Three movie theaters that had been scheduled to show the film later this month canceled their plans last week after receiving a flood of angry phone calls and warnings of protests by nationalists, who have been screaming slogans outside the Tokyo office of the Japanese distributor in recent months.

Protesters criticize the film as a betrayal of Japanese pride.

The American movie, this year's winner of the Academy Award for best documentary, features undercover footage of the dolphin hunt in a Japanese village and documents efforts by Ric O'Barry, a former trainer for the "Flipper" TV series, to stop the slaughter of dolphins for food.

Distributor Unplugged said it was negotiating with dozens of theaters throughout Japan, but no showing has been scheduled so far. The film was shown at the Tokyo International Film Festival in October but has not yet opened to the Japanese public.

Movie director Hirokazu Koreeda, journalist Soichiro Tahara and feminist Chizuko Ueno were among the 55 public personalities who signed a protest letter in which they said they were alarmed by the intimidation tactics used to pressure theaters to cancel the planned screenings.

"This is a film that has been widely shown abroad. If the work, which is about Japan, cannot be shown in Japan, it only underlines the weakness of the freedom of speech in Japan," they said in the statement sent to media and Unplugged on Monday.

They said that opinion may be divided on the film, but that meant it should be shown to a wide audience to encourage debate.

Most Japanese have never eaten dolphin meat. But some believe killing dolphins and whales is part of traditional culinary culture and resent the interference of outsiders focused on species protection.

"The work intentionally distorts Japanese people's food culture, and showing this will hurt many people's feelings," one of the protesting nationalist groups, Shuken Kaifuku wo Mezasu Kai, said in a recent statement.

"It's true Japanese may not feel happy about the way they are depicted in this film," Tahara said earlier this week in an interview broadcast on the Internet. "But blocking it is not right."

O'Barry blamed "a small minority of extremists" for the theater cancellations.

"The Japanese people have a right to see it if they want to," he said.